Presently, in the prior art which relates to the CT security inspection system generally comprises an X-ray device serving as a radiation source. The X-ray device emits the X-ray beam to scan the object to be inspected in the CT scanning channel. However, in the prior art, the device for fixing the X-ray device is not easy to adjust and the precision of the adjusting is poor. Also, since the collimator and the X-ray device are disposed separately, the conformability of the adjusting is bad and the structure of adjusting positioner for the X-ray device is caused to be large.